1. Field of the Invention
The present invention relates to a technology suitable for implementation in a microscope which comprises a low-powered lens unit, composed of a combination of a plurality of imaging lenses and objective lenses, and a continuously variable zoom unit, which realizes low magnification to high magnification, and performs electrical control of the switching of the lens unit and the movement speed of an observation subject.
2. Description of the Related Art
Due to improvement in the power of microscopes and sharp imaging technology, it is becoming possible to perform observation of sites as desired by the observer. However, it is becoming important not only to view the sites, but to also observe the interaction between cells, with focus on cell-level to tissue-level observation. Therefore, a microscope is required which can freely perform the observation of cells, observed at an extremely high magnification, to the observation of tissue, observed at a lower magnification, can further freely perform observation of the overall image of an organism, observed at an extremely low power, and can observe inter-cell information transmission which cannot be known through observation of a single cell. Thus, there is a need for a microscope which can freely perform low-powered observation to high-powered observation.
Current microscopes are electrically controlled and are very convenient. By the implementation of electrical control, the operator can smoothly adjust observation power, focus, and aperture, and furthermore, perform automatic control by setting observation conditions. Therefore, not only experienced operators, but also first-time operators, can be assured superior operation.
Consequently, electric focusing devices which electrically control low magnification to high magnification have been recently developed.
For example, in the Japanese Laid-Open Patent Publication No. (Heisei) 8-86965, a microscope having a revolving-type objective lens conversion mechanism, which automatically changes the speed at which a focusing mechanism is driven according to the currently observed objective lens power, is proposed. According to this proposal, the driving speed of the focusing mechanism is configured to be low when the objective lens power is high, and in addition, the driving speed of the focusing mechanism is configured to be high when the objective lens power is low. In this way, a microscope examiner can consistently perform focusing and operations in the same way, even when the magnifying power of the observation optical system is changed.
In addition, in the Japanese Laid-Open Patent Publication No. 2004-226882, a microscope which determines observation power by the combination of a continuously variable zoom mechanism and objective lens and to which the abovementioned focusing mechanism speed control is applied is proposed.
In the proposed microscopes described above, the speed of the focusing mechanism is uniquely determined to be a value set in advance by the power of the observation optical system. In addition, the calculation of magnifying power from observation imaging is particularly effective when the observation subject is small.